Fleischer graduated from the humanistic Gymnasium (grammar school) in Wiesbaden and was subsequently drafted into military service. After the end of the First World War in 1918, he studied composition with Professor Carl Kittel in Bayreuth until 1921, a course he had begun in 1913 but had to interrupt due to the war. Fleischer then worked as a composer and pianist in Wiesbaden, but soon resumed his studies, this time with Johanna Senfter in Oppenheim. He joined the Nazi Party (NSDAP) on August 1, 1931 (membership number 624,415)[1] and in the same year also the Combat League for German Culture.[2] In 1941, he became head of the music theory classes at the Luxembourg National Music School, and shortly thereafter also deputy director of the school. He relinquished this position in 1945 and returned to working freelance in Bayreuth. He spent the remaining years of his life living in his house with his wife Else, née Matthieu, where he died in 1981.